1. Field
The application relates to operation of doors that isolate smoke and flame from a non-burning area
2. Description of the Related Art
When a fire is detected in a building having fire doors, the fire doors must be kept closed. Keeping these doors closed helps to compartmentalize the fire. In the case of motorized rolling fire doors, fire detection devices are conventionally situated well above the doors or near the ceiling. A typical motorized rolling fire door will include a fusible link disposed a foot or more above the door. A fusible link is made from pieces of metal held together by solder designed to melt when it reaches a certain high temperature. When the fire detection device detects a fire because one or more of the fusible links has melted, the fire doors will be automatically closed. However, in many instances it may be desirable to take action if the temperature is higher than normal though not at the point where the fusible links melt. For example, in a cooler, temperatures normally would be less than 40 degrees F. During the early stages of a fire, the temperature in the cooler would be higher than normal but might not yet be enough to melt a fusible link. As another example, where the indoor temperature in an area is tightly controlled, a significant deviation from the temperature might indicate an abnormal situation warranting alerting a building supervisor or perhaps closing the doors.